Ecological selection of siderophore‐producing microbial taxa in response to heavy metal contamination

Abstract

Some microbial public goods can provide both individual and community‐wide benefits, and are open to exploitation by non‐producing species. One such example is the production of metal‐detoxifying siderophores. Here, we investigate whether conflicting selection pressures on siderophore production by heavy metals – a detoxifying effect of siderophores, and exploitation of this detoxifying effect – result in a net increase or decrease. We show that the proportion of siderophore‐producing taxa increases along a natural heavy metal gradient. A causal link between metal contamination and siderophore production was subsequently demonstrated in a microcosm experiment in compost, in which we observed changes in community composition towards taxa that produce relatively more siderophores following copper contamination. We confirmed the selective benefit of siderophores by showing that taxa producing large amounts of siderophore suffered less growth inhibition in toxic copper. Our results suggest that ecological selection will favour siderophore‐mediated decontamination, with important consequences for potential remediation strategies.

Genetic diversity, mobilisation and spread of the yersiniabactin-encoding mobile element ICEKp in Klebsiella pneumoniae populations

“…antigenic variation resulting in variable susceptibility to predators or host immunity [ 32 ]), or the trait has selective advantages only under certain conditions but high costs in others. Acquisition of ybt has benefits in certain iron-depleted conditions, which are presumably encountered in a wide range of environmental and host-associated niches [ 6 ]; siderophores including yersiniabactin also confer significant growth advantage in heavy metal contaminated soil irrespective of iron content [ 33 ]. Hence the dynamics of ICE Kp / ybt may reflect the diverse lifestyles of K. pneumoniae , which can vary between hosts and in the environment.…”

Biodiversity–function relationships in methanogenic communities

“…Studies of methanogenesis in natural soil communities have reported positive correlations between methane production (from an incubated soil sample) and the diversity of both methanogens and the total bacterial/archaeal communities (Wagner, Zona, Oechel, & Lipson, ; Yavitt, Yashiro, Cadillo‐Quiroz, & Zinder, ). However, any conclusions are potentially confounded by other environmental variables, such as pH, that can have a major role on community structure (Fierer et al., ; Hesse et al., ) and methanogenesis (Wagner et al., ). Other studies have focussed on correlations between community structure and methanogenesis under “common garden” laboratory conditions, where environmental factors are better controlled.…”

Screening of Heavy Metal-Immobilizing Bacteria and Its Effect on Reducing Cd2+ and Pb2+ Concentrations in Water Spinach (Ipomoea aquatic Forsk.)

“…Microorganisms are the main force in bioremediation of polluted soil and some functional microorganisms reduce the level of soil pollution [38]. Microbial communities are, additionally, also highly sensitive to environmental changes; therefore, they are considered indicators of local environmental conditions [26,39]. Heavy metals affect soil microorganisms mainly by altering the microbial community structure, reducing biomass, and affecting their biological activities [40].…”

“…Therefore, heavy metal-immobilizing bacteria screened from in situ heavy metal-contaminated plant rhizosphere soil show better environmental adaptability and higher ability for preventing crops from absorbing heavy metals [25]. Although high-throughput sequencing had been used to study the distribution of microbial populations under different heavy metal pollution conditions [23,26], few studies have examined the community differences of culturable bacteria and the proportion of heavy metal-immobilizing bacteria in water spinach rhizosphere soil with different levels of heavy metal pollution.…”